Hard carbon ultrafine powder washing system and method

Abstract

The invention relates to a carbon material preparation and post-treatment technology, and provides a hard carbon ultrafine powder washing system and method. The physical rejection rate of the particle impurity membrane is high, and the target product hard carbon is completely left on the circulation side; metal ions can be effectively removed through pH gradient dissolution and membrane micromolecule permeation, and the purity requirement of high-end hard carbon is met. Pulse backflushing and gas-liquid two-phase flow are coordinated to prevent blockage, the membrane flux maintenance initial value is effectively improved, and the service life of the membrane is prolonged. And cross-flow filtration is matched with the solid-phase interception unit, so that the recovery rate of the hard carbon ultrafine powder is very high, and product loss is avoided. The pressure control unit achieves seamless switching of liquid storage, buffering and washing links, the liquid supply concentration fluctuation is small, and long-time unattended operation is supported. The operation cost is obviously reduced, the chemical cleaning period is prolonged, the energy consumption is reduced, and the overall operation and maintenance cost is reduced.

Description

Technical Field

[0001] This invention relates to carbon material preparation and post-processing technology, specifically to a purification and separation technology in the preparation process of hard carbon ultrafine powder. By combining cross-flow membrane filtration with pH gradient washing, efficient separation of particulate impurities and metal ion impurities in hard carbon ultrafine powder is achieved. This technology is suitable for the post-processing stage of industrial production of hard carbon materials, and therefore provides a hard carbon ultrafine powder washing system and method. Background Technology

[0002] As one of the negative electrode materials for lithium-ion batteries, the purity of hard carbon materials largely determines the battery's cycle life, rate performance, and safety. Therefore, certain requirements are placed on the purity of hard carbon.

[0003] In existing technologies, plate and frame filter presses and centrifugal filters are generally used to remove particulate impurities, followed by soaking and stirring with detergent to dissolve metal ions before separation.

[0004] Hard carbon ultrafine powder is similar in size to particulate impurities, and traditional filtration methods easily lead to product loss or impurity residue, necessitating precise physical interception. Metal ions, such as Fe... 3+ Ca 2+ Due to their extremely small size, they cannot be directly retained by the membrane and must be separated through chemical dissolution, while also needing to be compatible with the pH tolerance of the hard carbon. Membrane fouling leads to efficiency degradation; hard carbon particles easily adhere to / clog membrane pores, causing a rapid decline in membrane flux. Therefore, it is necessary to address membrane anti-fouling and flux maintenance issues during long-term operation. Precise pressure / flow control is required in the storage, washing, and supply processes to avoid process interruptions, product leakage, or pH gradient disruption. A stable supply of acidic / neutral / alkaline washing solutions is essential to ensure efficient, stepwise removal of metal ions while avoiding damage to the hard carbon structure.

[0005] Therefore, finding a suitable washing method for hard carbon ultrafine powder is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] Therefore, in order to solve the problems of poor purification accuracy and low efficiency mentioned in the prior art, it is necessary to propose a hard carbon ultrafine powder washing system and method that can improve purification accuracy.

[0007] In a first aspect, this application provides a hard carbon ultrafine powder washing system, including at least one movable liquid storage unit, at least one cross-flow membrane filtration unit, and a solid phase retention unit; The liquid storage unit, the cross-flow membrane filtration unit, and the solid phase retention unit are connected in a conductive manner. The liquid storage unit contains a suspension of hard carbon ultrafine powder mixed with the initial washing medium and is equipped with a liquid storage pressure control unit. The cross-flow membrane filtration unit includes an acidic washing tank, a neutral washing tank, and an alkaline washing tank connected in sequence. Each washing tank is equipped with a filter membrane, a membrane treatment unit, and a cross-flow tank pressure control unit. The acidic washing tank, the neutral washing tank, and the alkaline washing tank store washing media with a pH gradient that increases sequentially. Particulate and metal ion impurities in the suspension are removed simultaneously by the washing medium and the filter membrane with a sequentially increasing pH gradient in the cross-flow membrane filtration unit. Maintain stable membrane flux through membrane treatment units; The pressure control system, consisting of a liquid storage pressure control unit and a tank pressure control unit, maintains stable flow of the suspension in a single cross-flow membrane filtration unit and seamless switching between multiple liquid storage units to be treated. The solid phase retention unit retains the suspension output from the cross-flow membrane filtration unit in a solid phase, and after drying, obtains clean hard carbon ultrafine powder.

[0008] Furthermore, at least two liquid storage units to be treated form a liquid storage system connected in parallel, at least two cross-flow membrane filtration units form a filtration system connected in parallel, the filtration system also includes a buffer tank, multiple cross-flow membrane filtration units connected in parallel are connected to one buffer tank, and the liquid storage system is connected in parallel to one infusion tube and leads to the buffer tank.

[0009] Furthermore, the liquid storage unit to be treated includes a storage tank, an outlet at the top of the storage tank, and an outlet pipe. The storage tank is divided into a liquid zone occupied by a suspension and an air zone occupied by gas. One end of the outlet pipe extends to the bottom of the liquid, and the other end passes through the outlet and is connected to the delivery pipe. The liquid pressure control unit of the liquid storage unit to be treated includes a storage pressure switch, and an outlet switch is provided on the outlet pipe.

[0010] Furthermore, the buffer tank is equipped with a buffer pressure control unit, which includes a buffer pressure switch, and an external power pump unit is installed outside the buffer tank.

[0011] Furthermore, a working washing unit is composed of a movable liquid storage unit, a cross-flow membrane filtration unit, and a solid phase retention unit. The liquid storage pressure control unit of the liquid storage unit controls the liquid storage tank to be in a high-pressure zone, and the buffer pressure control unit of the buffer tank of the cross-flow membrane filter unit controls the buffer tank to be in a low-pressure zone. The suspension is transferred from the liquid storage unit, the outlet pipe, and the delivery pipe to the buffer tank through the pressure difference between the high-pressure zone and the low-pressure zone. The pressure control unit of the liquid storage unit continuously replenishes air to maintain the high-pressure zone within the working range. The buffer tank continuously feeds the suspension into the acid washing tank via an external power pump unit.

[0012] Furthermore, the cross-flow membrane filtration unit also includes an acidic storage tank, a neutral storage tank, and an alkaline storage tank. Multiple acidic washing tanks of the cross-flow membrane filtration unit are connected in parallel with the acidic storage tank, multiple neutral washing tanks are connected in parallel with the neutral storage tank, and multiple alkaline washing tanks are connected in parallel with the alkaline storage tank. The acidic storage tank is a continuously supplied acidic washing tank to maintain the concentration of acidic washing solution within the working range. The neutral storage tank is a continuously supplied neutral washing tank to maintain the concentration of neutral washing solution within the working range. The alkaline storage tank is a continuously supplied alkaline washing tank to maintain the concentration of alkaline washing solution within the working range.

[0013] Furthermore, a stable pressure difference is maintained between the acid wash tank, the neutral wash tank, and the alkaline wash tank by the cross-flow tank pressure control unit to drive the suspension to continuously flow through the acid wash tank, the neutral wash tank, and the alkaline wash tank.

[0014] Furthermore, the pressure inside the acidic reservoir is higher than that of one or more connected acidic wash tanks to drive the acidic wash solution to be continuously supplied from the acidic reservoir to one or more acidic wash tanks.

[0015] Furthermore, the membrane treatment unit includes a pulse backflush system and a gas-liquid two-phase flow system; The pulse backwash system includes a backwash line that sprays high-pressure cleaning fluid. The backwash line is connected from the membrane module of the filter membrane to the membrane surface in reverse. The pulse backwash system is also equipped with a solenoid valve and a control unit. The control unit triggers the backwash action through a timer or a membrane flux sensor. The gas-liquid two-phase system includes a gas-liquid mixer disposed on one side of the membrane surface of the filter membrane, which mixes the compressed gas and the suspension and then flows parallel to the membrane surface.

[0016] Secondly, this application provides a method for washing ultrafine charcoal powder, including the following steps: Obtain ultrafine hard carbon powder and mix it with the initial washing medium, then disperse it to obtain a suspension; The suspension is fed into the cross-flow membrane filtration unit and passes through the acid washing tank, neutral washing tank and alkaline washing tank in sequence. The particulate impurities and metal ion impurities in the suspension are removed by the combination of pH gradient concentration medium and filter membrane. Simultaneously perform pulse backflushing and gas-liquid two-phase flow treatment on the surface of the filter membrane to maintain stable membrane flux; The suspension, after being washed with a pH gradient concentration medium, is then passed through a solid phase retention unit to retain the solid phase, and then dried to obtain clean hard carbon ultrafine powder.

[0017] Furthermore, the step of feeding the suspension into the cross-flow membrane filtration unit includes: Select one liquid storage tank from the parallel liquid storage units to be processed as the current working unit, and shut down the other liquid storage units to be processed; The liquid storage pressure control unit replenishes air to the air zone of the liquid storage tank to maintain a high-pressure zone inside the liquid storage tank; The buffer pressure control unit maintains the buffer tank in a low-pressure zone, opens the liquid outlet switch on the liquid outlet pipe, and drives the suspension from the storage tank into the buffer tank through the liquid outlet pipe and the liquid delivery pipe by the pressure difference between the high-pressure zone and the low-pressure zone. When the level of the suspension in the current discharge unit is lower than the threshold, a seamless switching action is triggered, opening the discharge switch of the next storage unit to be processed, and simultaneously closing the discharge switch of the current unit to maintain stable pressure in the infusion tube. The external power pump unit of the buffer tank continuously feeds the suspension into the acid washing tank of the cross-flow membrane filter unit at a set flow rate; Repeat the above steps until all suspensions in the storage units to be processed have been transferred to the buffer tank.

[0018] Furthermore, the steps for supplying washing solutions to the acidic, neutral, and alkaline washing tanks include: Acidic, neutral, and alkaline storage tanks store washing solutions of corresponding pH values, and the concentration of the washing solution is monitored in real time by a concentration sensor. The pressure control unit of the acidic storage tank maintains the internal pressure higher than that of the parallel acidic washing tanks, driving the acidic washing liquid to continuously flow into the acidic washing tank to replenish the washing liquid lost due to filtration. Similarly, the neutral liquid storage tank maintains a higher pressure than the parallel neutral washing tanks, and continuously replenishes the neutral washing liquid; Similarly, the alkaline storage tank maintains a higher pressure than the parallel alkaline washing tanks, and continuously replenishes the alkaline washing liquid; The cross-flow tank pressure control unit maintains the pressure gradient between the acidic wash tank, the neutral wash tank, and the alkaline wash tank, driving the suspension to flow through the three wash tanks in sequence.

[0019] The hard carbon ultrafine powder washing system and method provided in this application have the following advantages: The membrane physical rejection rate for particulate impurities is high, and the target product, hard carbon, remains completely on the circulation side; metal ions can be effectively removed through pH gradient dissolution and membrane small molecule permeation, meeting the purity requirements of high-end hard carbon. Pulse backflushing and coordinated gas-liquid two-phase flow prevent clogging, effectively improving membrane flux and extending membrane life. Cross-flow filtration combined with a solid-phase retention unit results in a high recovery rate of hard carbon ultrafine powder, preventing product loss. The pressure control unit enables seamless switching between liquid storage, buffering, and washing stages, with minimal fluctuations in supply concentration, supporting long-term unattended operation. Operating costs are significantly reduced, chemical cleaning cycles are extended, energy consumption is reduced, and overall maintenance costs are lowered.

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a hard carbon ultrafine powder washing system in one embodiment; Figure 2 This is a schematic flowchart of a method for washing ultrafine hard carbon powder in one embodiment.

[0022] Figure label: 10. Infusion tubing; 11. Storage tank; 12. Air zone; 13. Liquid zone; 14. Storage pressure control unit; 15. Storage pressure switch; 16. Discharge tubing; 17. Discharge switch; 20. Buffer tank; 21. Buffer pressure control unit; 30. External power pump unit. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] Example 1

[0025] This embodiment relates to carbon material preparation and post-processing technology, specifically purification and separation technology in the preparation process of hard carbon ultrafine powder. This embodiment focuses on high-performance energy storage materials, such as lithium-ion battery anode materials. Through the synergistic combination of cross-flow membrane filtration and pH gradient washing, hard carbon ultrafine powder is deeply washed and purified, achieving efficient removal of particulate impurities and metal ion impurities in hard carbon ultrafine powder. It is applicable to the post-processing process of hard carbon material production.

[0026] In actual production, existing technologies mainly use centrifugal separation, plate and frame filtration and other methods to intercept and remove impurities, and then use detergent to soak and stir to dissolve metal ions and then separate them. (1) In centrifugal separation washing, the suspension is put into a centrifuge and solid-liquid separation is achieved under the action of centrifugal force. After separation, the supernatant of soluble impurities is removed, the bottom wet powder is retained, detergent is added to the wet powder, and after stirring and separation, centrifugation is repeated until the separation is clean to a certain purity. (2) In plate and frame filtration washing, the suspension is pumped into a plate and frame filter press, and the hard carbon ultrafine powder is intercepted through the filter membrane or filter screen to obtain a filter cake. The washing medium is introduced into the filter cake, and the detergent is allowed to penetrate the filter cake by gravity or pressure while taking away impurities. The above steps are repeated until the separation is clean to a certain purity. However, since the hard carbon ultrafine powder and particulate impurities are similar in size, traditional filtration is prone to product loss or impurity residue, such as metal ions Fe. 3+ Ca 2+ If certain substances cannot be directly retained by the membrane, they need to be separated by chemical dissolution. However, the above two methods are difficult to achieve this process efficiently. Membrane fouling leads to a decrease in separation efficiency. Hard carbon particles are prone to adhering and even clogging the membrane pores, resulting in a decrease in separation efficiency. In order to ensure long-term stable operation, it is necessary to solve the problems of membrane anti-fouling and flux maintenance during long-term operation.

[0027] This embodiment provides a hard charcoal ultrafine powder washing system, see reference. Figure 1 As shown, it includes at least one movable liquid storage unit, at least one cross-flow membrane filtration unit, and a solid-phase retention unit; the liquid storage unit, the cross-flow membrane filtration unit, and the solid-phase retention unit are electrically connected; the liquid storage unit stores a suspension of hard carbon ultrafine powder mixed with the initial washing medium and is equipped with a liquid storage pressure control unit; the cross-flow membrane filtration unit includes an acidic washing tank, a neutral washing tank, and an alkaline washing tank connected in sequence, each washing tank being equipped with a filter membrane, a membrane treatment unit, and a cross-flow tank pressure control unit. The internal storage contains washing media with a sequentially increasing pH gradient; particulate impurities and metal ion impurities in the suspension are simultaneously removed by the washing media with a sequentially increasing pH gradient and the filter membrane in the cross-flow membrane filtration unit; the membrane treatment unit maintains stable membrane flux; the pressure control system composed of the liquid storage pressure control unit and the tank pressure control unit maintains stable flow of the suspension in a single cross-flow membrane filtration unit and seamless switching between multiple liquid storage units to be treated; the solid phase retention unit retains the suspension output from the cross-flow membrane filtration unit in the solid phase, and after drying, clean hard carbon ultrafine powder is obtained.

[0028] It should be noted that the storage unit contains a suspension of ultrafine hard carbon powder mixed with the initial washing medium. The ultrafine hard carbon powder and deionized water are mixed at a solid-liquid ratio of 1:10 to 1:20. The initial hard carbon agglomerates are broken up by a high-speed shear disperser, so that the particle diameter of the dispersed hard carbon agglomerates is less than or equal to 50 μm, forming a uniform suspension. The uniformity of the suspension is maintained by stirring to prevent the hard carbon particles from settling, which facilitates subsequent filtration. The outlet pipeline of the storage tank of the storage pressure control unit is equipped with a regulating valve and a pressure transmitter. The regulating valve is controlled by a PLC to stabilize the pressure in the storage tank and ensure that the suspension flows steadily into the cross-flow membrane filtration unit; or the suspension flows into the cross-flow membrane filtration unit through a circulation pump.

[0029] The cross-flow membrane filtration unit removes impurities through a three-stage washing tank system, utilizing a pH gradient. The suspension is passed sequentially through an acidic washing tank, a neutral washing tank, and an alkaline washing tank. The suspension is then fed into the cross-flow membrane filtration unit, where washing solutions of different properties (acidic, neutral, and alkaline) are used to target and remove impurities. Specifically, the suspension is first passed into the acidic washing tank, which contains an acidic solution with a pH of 2-3, such as 0.5% dilute hydrochloric acid, to specifically remove sodium (Na₂O₃). + Fe 3+ The suspension is then passed from the acidic washing tank to the neutral washing tank, which contains deionized water to remove residual acid radicals. Next, the suspension from the neutral washing tank is passed to the alkaline washing tank, which contains a weakly alkaline solution with a pH of 8-9 to remove residual acid and metal ions. This gradient concentration washing medium sequentially removes different types of impurities from the micropores of the ultrafine hard carbon powder, solving the problem of high impurity residue rates in traditional single-wash solutions. Furthermore, each washing tank is equipped with a filter membrane, a membrane treatment unit, and a cross-flow pressure control unit. When the suspension enters the washing tank, it passes through the filter membrane to remove large particles. The membrane treatment unit includes a pulse backflushing system and a gas-liquid two-phase flow system. The pulse backflushing system effectively removes hard carbon particles deposited on the membrane surface, while the gas-liquid two-phase flow system flushes the membrane surface, reducing the probability of particle adhesion, improving long-term stability, and preventing excessive impurity deposition and clogging.

[0030] The solid phase retention unit retains the suspension output from the cross-flow membrane filtration unit and obtains clean hard carbon ultrafine powder after drying. Specifically, the solid phase retention unit receives the suspension output from the cross-flow membrane filtration unit, retains the hard carbon ultrafine powder through a precision filter, and after the filtrate enters the wastewater treatment system, the retained hard carbon filter cake is vacuum dried to reduce the moisture content to 2wt% to obtain clean hard carbon ultrafine powder.

[0031] The beneficial effects of the solution provided in this embodiment are as follows: The membrane physical rejection rate for particulate impurities is high, and the target product, hard carbon, is completely retained on the circulation side. The cross-flow membrane filtration unit includes acidic, neutral, and alkaline washing tanks. Metal ions can be effectively removed through pH gradient dissolution and membrane small molecule permeation, meeting the purity requirements of high-end hard carbon. Through pH gradient cross-flow membrane filtration and pressure synergistic control, efficient removal of particulate impurities and metal ions from ultrafine hard carbon is achieved, while ensuring the long-term operational stability of the membrane treatment unit. Pulse backflushing and gas-liquid two-phase flow coordination prevent clogging, effectively improving membrane flux to maintain its initial value and extending membrane life. The cross-flow filtration and solid-phase retention unit work together to achieve a high recovery rate of ultrafine hard carbon powder, preventing product loss. The pressure control unit enables seamless switching between liquid storage, buffering, and washing stages, with minimal fluctuations in supply concentration, supporting long-term unattended operation. Operating costs are significantly reduced, chemical cleaning cycles are extended, energy consumption is reduced, and overall maintenance costs are lowered.

[0032] Example 2 Based on Embodiment 1, this embodiment provides a further solution: at least two liquid storage units to be processed form a liquid storage system connected in parallel, at least two cross-flow membrane filtration units form a filtration system connected in parallel, the filtration system also includes a buffer tank, multiple cross-flow membrane filtration units connected in parallel are connected to one buffer tank, and the liquid storage system is connected in parallel to one infusion pipe and connected to the buffer tank.

[0033] It should be noted that at least two parallel storage units for treating liquids are configured for capacity expansion, and at least two cross-flow membrane filtration units are installed to improve efficiency. This allows for flexible capacity expansion and seamless switching during failures. Furthermore, the buffer tank ensures the stability of the pH gradient washing process through buffer regulation. Each storage unit is equipped with a pneumatic shut-off valve and a check valve at its outlet, and the main delivery line is equipped with a total flow regulating valve. The buffer tank is located between the parallel storage system and the parallel cross-flow membrane filtration units. By increasing the number of storage units and cross-flow membrane filtration units, capacity can be flexibly expanded to meet different production scales. The modular design facilitates future upgrades.

[0034] Example 3 Based on Embodiment 2, this embodiment provides a further solution: the liquid storage unit to be processed includes a liquid storage tank, an outlet located at the top of the liquid storage tank, and an outlet pipe. The liquid storage tank is divided into a liquid area occupied by a suspension and an air area occupied by gas. One end of the outlet pipe extends to the bottom of the liquid, and the other end passes through the outlet and is connected in parallel to the delivery pipe. The liquid outlet pressure control unit of the liquid storage unit to be processed includes a liquid storage pressure switch, and an outlet switch is provided on the outlet pipe.

[0035] It should be noted that the liquid storage unit in this embodiment is an integrated pressure-type liquid storage device, capable of stably storing hard carbon ultrafine powder suspension and precisely controlling the liquid pressure. The liquid storage unit includes a storage tank, a liquid outlet, and a liquid outlet pipe. The liquid tank is naturally divided into a liquid zone and an air zone by the suspension level. The liquid outlet pressure control unit stabilizes the liquid outlet pressure at a preset value through closed-loop feedback control.

[0036] Example 4 Based on Embodiment 3, this embodiment provides a further solution: the buffer tank is equipped with a buffer pressure control unit, which includes a buffer pressure switch, and an external power pump unit is installed outside the buffer tank.

[0037] It should be noted that the buffer tank in this embodiment is an intermediate buffer device with pressure control and power enhancement functions, located between the parallel liquid storage system and the parallel cross-flow membrane filtration unit. On the one hand, the buffer tank can be used to balance the inlet flow fluctuations of the liquid storage unit to be treated. A stable inlet pressure is provided to the subsequent filtration system through the external power pump unit in the pressure control unit. On the other hand, the buffer tank can be used to premix the suspension, avoiding sudden changes in pH concentration.

[0038] Example 5 Based on Embodiment 4, this embodiment provides a further solution, which selects one movable liquid storage unit, one cross-flow membrane filtration unit and a solid phase retention unit to form a working washing unit. The liquid storage pressure control unit of the liquid storage unit controls the liquid storage tank to be in a high-pressure zone, and the buffer pressure control unit of the buffer tank of the cross-flow membrane filter unit controls the buffer tank to be in a low-pressure zone. The suspension is transferred from the liquid storage unit, the outlet pipe, and the delivery pipe to the buffer tank through the pressure difference between the high-pressure zone and the low-pressure zone. The pressure control unit of the liquid storage unit continuously replenishes air to maintain the high-pressure zone within the working range. The buffer tank continuously feeds the suspension into the acid washing tank via an external power pump unit.

[0039] It should be noted that this embodiment uses pressure difference to drive the working washing unit, which consists of a movable liquid storage unit, a cross-flow membrane filtration unit with a buffer tank, and a solid phase retention unit. The liquid is driven by the pressure difference between the high-pressure zone and the low-pressure zone, replacing the traditional pump drive and reducing the risk of particle shearing and pipeline blockage.

[0040] Example 6 Based on Embodiment 1, this embodiment provides a further solution: the cross-flow membrane filtration unit further includes an acidic storage tank, a neutral storage tank, and an alkaline storage tank. Multiple acidic washing tanks of the cross-flow membrane filtration unit are connected in parallel with the acidic storage tank, multiple neutral washing tanks are connected in parallel with the neutral storage tank, and multiple alkaline washing tanks are connected in parallel with the alkaline storage tank. The acidic storage tank is a continuously supplied acidic washing tank to maintain the concentration of acidic washing solution within the working range. The neutral storage tank is a continuously supplied neutral washing tank to maintain the concentration of neutral washing solution within the working range. The alkaline storage tank is a continuously supplied alkaline washing tank to maintain the concentration of alkaline washing solution within the working range.

[0041] It should be noted that by supplying liquid to multiple washing tanks in parallel through a storage tank, the washing liquid is centrally stored and distributed, improving the system's throughput and availability. The flow rate, level, and fault linkage control of the storage tank and washing tanks ensure the long-term continuity and stability of the three-stage washing process.

[0042] Example 7 Based on Embodiment Six, this embodiment provides a further solution: a stable pressure difference is maintained between the acid washing tank, the neutral washing tank, and the alkaline washing tank by a cross-flow tank pressure control unit to drive the suspension to continuously flow through the acid washing tank, the neutral washing tank, and the alkaline washing tank.

[0043] It should be noted that by using the cross-flow tank pressure control unit, a stable pressure difference is maintained between the acidic washing tank, the neutral washing tank, and the alkaline washing tank, thereby achieving the transfer between the washing tanks in the hard carbon suspension, replacing the traditional pump drive, and reducing the risk of particle shear damage and pipeline blockage.

[0044] Example 8 Based on Example 6, this example provides a further solution in which the pressure inside the acidic storage tank is higher than that of one or more connected acidic washing tanks to drive the acidic washing liquid to be continuously supplied from the acidic storage tank to one or more acidic washing tanks.

[0045] It should be noted that the pressure inside the acidic storage tank in this embodiment is higher than the pressure inside one or more connected acidic washing tanks. The pressure difference between the storage tank and the washing tank enables automatic pump-free supply of acidic washing liquid, thereby improving the stability of the washing liquid concentration and the system operating efficiency.

[0046] Example 9 Based on Embodiment 1, this embodiment provides a further solution, wherein the membrane treatment unit includes a pulse backflush system and a gas-liquid two-phase flow system; The pulse backwash system includes a backwash line that sprays high-pressure cleaning fluid. The backwash line is connected from the membrane module of the filter membrane to the membrane surface in reverse. The pulse backwash system is also equipped with a solenoid valve and a control unit. The control unit triggers the backwash action through a timer or a membrane flux sensor. The gas-liquid two-phase system includes a gas-liquid mixer disposed on one side of the membrane surface of the filter membrane. The gas-liquid mixer mixes the compressed gas with the suspension and then flows parallel to the membrane surface.

[0047] It should be noted that the pulse backwash system includes a backwash line that sprays high-pressure cleaning fluid. This backwash line connects laterally to the membrane surface through the membrane module and is equipped with a fast-response solenoid valve. The control unit triggers the backwash action via a timer or membrane flux sensor. Specifically, during normal filtration, the suspension flows cross-currently along the membrane surface. Particulate matter easily adheres to the membrane surface, clogging the pores and causing a decrease in membrane flux. In this embodiment, the backwash line spraying high-pressure cleaning fluid disperses the particulate matter adhering to the membrane surface. The gas-liquid two-phase system addresses membrane fouling through gas-liquid mixing and bubble agitation. The gas-liquid two-phase system operates continuously during normal filtration, continuously preventing the deposition of hard carbon particles on the membrane surface through bubble agitation, reducing the chance of particulate matter adhesion. When the gas-liquid two-phase flow cannot completely prevent the flux decrease, pulsed backwash is activated, using instantaneous high-pressure reverse impact to remove deep blockages. The combination of pulse backwash and the gas-liquid two-phase flow system enables the cross-flow membrane filtration unit to achieve efficient, stable, and low-cost filtration through continuous protection and intermittent cleaning.

[0048] Example 10 This embodiment provides a method for washing ultrafine charcoal powder. (See attached document.) Figure 1 and Figure 2 As shown, the steps include: Step S100: Obtain hard carbon ultrafine powder and mix it with the initial washing medium, and obtain a suspension after dispersion treatment; In step S200, the suspension is fed into the cross-flow membrane filtration unit and passes through the acid washing tank, neutral washing tank and alkaline washing tank in sequence. The particulate impurities and metal ion impurities in the suspension are removed by the combination of pH gradient concentration medium and filter membrane. Step S300: Simultaneously perform pulse backwashing and gas-liquid two-phase flow treatment on the surface of the filter membrane to maintain stable membrane flux. In step S400, the suspension washed with a pH gradient concentration medium is passed through a solid phase retention unit to retain the solid phase, and then dried to obtain clean hard carbon ultrafine powder.

[0049] It should be noted that in this embodiment, the particulate impurity membrane has a high physical rejection rate, and the target product, hard carbon, remains entirely on the circulation side. The cross-flow membrane filtration unit includes acidic, neutral, and alkaline washing tanks. Metal ions are effectively removed through pH gradient dissolution and membrane small molecule permeation, meeting the purity requirements of high-end hard carbon. Through pH gradient cross-flow membrane filtration and pressure synergistic control, efficient removal of particulate impurities and metal ions from ultrafine hard carbon is achieved, while ensuring the long-term operational stability of the membrane treatment unit. Pulse backflushing and gas-liquid two-phase flow coordination prevent clogging, effectively improving membrane flux to maintain its initial value and extending membrane life. The cross-flow filtration unit, in conjunction with the solid-phase retention unit, achieves a high recovery rate of ultrafine hard carbon powder, preventing product loss. The pressure control unit enables seamless switching between storage, buffering, and washing stages, with minimal fluctuations in supply concentration, supporting long-term unattended operation. Operating costs are significantly reduced, chemical cleaning cycles are extended, energy consumption is reduced, and overall maintenance costs are lowered.

[0050] Example 11 Based on Example 10, this example provides a further solution, wherein the step of inputting the suspension into the cross-flow membrane filtration unit includes: Select one liquid storage tank from the parallel liquid storage units to be processed as the current working unit, and shut down the other liquid storage units to be processed; The liquid storage pressure control unit replenishes air to the air zone of the liquid storage tank to maintain a high-pressure zone inside the liquid storage tank; The buffer pressure control unit maintains the buffer tank in a low-pressure zone, opens the liquid outlet switch on the liquid outlet pipe, and drives the suspension from the storage tank into the buffer tank through the liquid outlet pipe and the liquid delivery pipe by the pressure difference between the high-pressure zone and the low-pressure zone. When the level of the suspension in the current working liquid storage unit is lower than the threshold, a seamless switching action is triggered, opening the outlet switch of the next liquid storage unit and simultaneously closing the outlet switch of the current unit to maintain stable pressure in the infusion tube. The external power pump unit of the buffer tank continuously feeds the suspension into the acid washing tank of the cross-flow membrane filter unit at a set flow rate; Repeat the above steps until all suspensions in the storage units to be processed have been transferred to the buffer tank.

[0051] It should be noted that this embodiment solves the problems of low efficiency, large quality fluctuations, and frequent failures of traditional pump-driven transmission by using pressure difference drive, seamless switching, and continuous coordinated control of buffer tank pressure stabilization, providing core technical support for the continuous and high-quality production of hard carbon ultrafine powder washing system.

[0052] Example 12 Based on Example 10, this example provides a further solution, wherein the steps for supplying washing liquid to the acidic washing tank, neutral washing tank, and alkaline washing tank include: Acidic, neutral, and alkaline storage tanks store washing solutions of corresponding pH values, and the concentration of the washing solution is monitored in real time by a concentration sensor. The pressure control unit of the acidic storage tank maintains the internal pressure higher than that of the parallel acidic washing tanks, driving the acidic washing liquid to continuously flow into the acidic washing tank to replenish the washing liquid lost due to filtration. Similarly, the neutral liquid storage tank maintains a higher pressure than the parallel neutral washing tanks, and continuously replenishes the neutral washing liquid; Similarly, the alkaline storage tank maintains a higher pressure than the parallel alkaline washing tanks, and continuously replenishes the alkaline washing liquid; The cross-flow tank pressure control unit maintains the pressure gradient between the acidic wash tank, the neutral wash tank, and the alkaline wash tank, driving the suspension to flow through the three wash tanks in sequence.

[0053] It should be noted that this embodiment uses the pressure difference of three-stage storage tanks to drive the coordinated operation of liquid supply and washing pressure gradient, thereby extending the chemical cleaning cycle, reducing energy consumption, and lowering the overall operation and maintenance costs.

[0054] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly set on the other component; when a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to the other component.

[0055] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" or "several" means two or more, unless otherwise explicitly specified.

[0056] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

[0057] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0058] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A hard carbon ultrafine powder washing system, characterized in that, The system comprises at least one movable liquid storage unit, at least one cross-flow membrane filtration unit, and a solid-phase interception unit. The liquid storage unit, the cross-flow membrane filtration unit, and the solid-phase interception unit are connected in series. The liquid storage unit stores a suspension of hard carbon ultrafine powder mixed with an initial washing medium and is provided with a liquid storage pressure control unit. The cross-flow membrane filtration unit comprises sequentially connected acid washing tanks, neutral washing tanks, and alkaline washing tanks, each of which is provided with a filter membrane, a membrane treatment unit, and a cross-flow tank pressure control unit, and each of the acid washing tanks, the neutral washing tanks, and the alkaline washing tanks stores a washing medium with a pH gradient that increases sequentially. The cross-flow membrane filtration unit simultaneously removes particulate impurities and metal ion impurities in the suspension through the washing medium with a pH gradient that increases sequentially and the filter membrane. The membrane treatment unit maintains the stability of the membrane flux. The pressure control system composed of the liquid storage pressure control unit and the tank pressure control unit maintains the stable flow of the suspension in the cross-flow membrane filtration unit and the seamless switching between the multiple liquid storage units. The solid-phase interception unit performs solid-phase interception on the suspension output by the cross-flow membrane filtration unit, and obtains clean hard carbon ultrafine powder after drying treatment.

2. The hard carbon ultrafine powder washing system according to claim 1, characterized in that, The system comprises at least two liquid storage units connected in parallel, at least two cross-flow membrane filtration units connected in parallel, and a buffer tank.

3. The hard carbon ultrafine powder washing system according to claim 2, characterized in that: The liquid storage unit comprises a liquid storage tank, a liquid outlet at the top of the liquid storage tank, and a liquid outlet pipe, the liquid storage tank is divided into a liquid zone occupied by the suspension and an air zone occupied by gas, one end of the liquid outlet pipe extends into the bottom of the liquid zone, the other end of the liquid outlet pipe passes through the liquid outlet and is connected to the liquid outlet pipe, the liquid outlet pressure control unit of the liquid storage unit comprises a liquid storage pressure switch, and a liquid outlet switch is arranged on the liquid outlet pipe.

4. The hard carbon ultrafine powder washing system according to claim 3, characterized in that: The buffer tank is provided with a buffer pressure control unit, the buffer pressure control unit comprises a buffer pressure switch, and an external power pump unit is arranged outside the buffer tank.

5. The hard carbon ultrafine powder washing system according to claim 4, characterized in that: The system comprises one movable liquid storage unit, one cross-flow membrane filtration unit, and a solid-phase interception unit. The liquid storage pressure control unit of the liquid storage unit controls the liquid storage tank to be a high-pressure zone, the buffer pressure control unit of the buffer tank of the cross-flow membrane filtration unit controls the buffer tank to be a low-pressure zone, the suspension is transferred from the liquid storage unit, the liquid outlet pipe, and the liquid outlet pipe to the buffer tank through the pressure difference between the high-pressure zone and the low-pressure zone, and the pressure control unit of the liquid storage unit continuously supplies air to maintain the high-pressure zone within the working range. The buffer tank continuously inputs the suspension into the acid washing tank through the external power pump unit.

6. The hard carbon ultrafine powder washing system according to claim 1, characterized in that, The cross-flow membrane filtration unit further comprises an acid storage tank, a neutral storage tank, and an alkaline storage tank, the multiple acid washing tanks of the cross-flow membrane filtration unit are connected in parallel with the acid storage tank, the multiple neutral washing tanks are connected in parallel with the neutral storage tank, and the multiple alkaline washing tanks are connected in parallel with the alkaline storage tank. The acid storage tank continuously supplies liquid to the open acid washing tank to maintain the concentration of the acid washing liquid in the acid storage tank within the working range, the neutral storage tank continuously supplies liquid to the open neutral washing tank to maintain the concentration of the neutral washing liquid within the working range, and the alkaline storage tank continuously supplies liquid to the open alkaline washing tank to maintain the concentration of the alkaline washing liquid within the working range.

7. The hard carbon ultrafine powder scrubbing system according to claim 6, wherein, The cross-flow tank pressure control unit maintains a stable pressure difference between the acid washing tank, the neutral washing tank and the alkaline washing tank to drive the suspension to continuously flow through the acid washing tank, the neutral washing tank and the alkaline washing tank.

8. The hard carbon ultrafine powder washing system according to claim 6, wherein, The pressure in the acid storage tank is higher than that in one or more open acid washing tanks to drive the acid washing liquid to continuously supply liquid to the one or more open acid washing tanks.

9. The hard carbon ultrafine powder washing system according to claim 1, wherein, The membrane treatment unit comprises a pulse backflush system and a gas-liquid two-phase flow system; The pulse backflush system comprises a backflush pipeline for spraying high-pressure cleaning liquid, the backflush pipeline is reversely connected to the membrane surface from the permeation side of the membrane module, and the pulse backflush system is further provided with a battery valve and a control unit, and the control unit triggers the backflush action through a timer or a membrane flux sensor; The gas-liquid two-phase system comprises a gas-liquid mixer arranged on one side of the membrane surface of the filtration membrane, and the gas-liquid mixer flows in parallel with the membrane surface after mixing compressed gas and the suspension.

10. A hard carbon ultrafine powder washing method, characterized by, The method comprises the steps of: obtaining hard carbon ultrafine powder and mixing it with initial washing medium, and obtaining a suspension after dispersion treatment; inputting the suspension into the cross-flow membrane filtration unit, sequentially passing through the acid washing tank, the neutral washing tank and the alkaline washing tank, and removing particulate impurities and metal ion impurities in the suspension through the cooperation of the pH gradient concentration medium and the filtration membrane; synchronously performing pulse backflush and gas-liquid two-phase flow treatment on the surface of the filtration membrane to maintain stable membrane flux; after the suspension is washed by the pH gradient concentration medium, the suspension is subjected to solid-phase interception in the solid-phase interception unit, and then after drying treatment, clean hard carbon ultrafine powder is obtained.

11. The hard carbon ultrafine powder washing method according to claim 10, wherein, The step of inputting the suspension into the cross-flow membrane filtration unit comprises: selecting one to-be-treated storage tank from the parallel to-be-treated storage units as a current working unit, and closing other to-be-treated storage units; the storage pressure control unit supplies air to the air area of the storage tank to maintain a high-pressure area in the storage tank; the buffer pressure control unit maintains a low-pressure area in the buffer tank, opens the liquid outlet switch on the liquid outlet pipe, and drives the suspension to flow from the storage tank to the buffer tank through the liquid outlet pipe and the liquid delivery pipe through the pressure difference between the high-pressure area and the low-pressure area; when the liquid level of the suspension in the current liquid outlet unit is lower than a threshold value, a seamless switching action is triggered, the liquid outlet switch of the next to-be-treated storage unit is opened, and the liquid outlet switch of the current unit is simultaneously closed to maintain stable pressure in the liquid delivery pipe; the external power pump unit of the buffer tank continuously inputs the suspension to the acid washing tank of the cross-flow membrane filtration unit at a set flow rate; the above steps are repeated until the suspensions in all to-be-treated storage units are transferred to the buffer tank.

12. The hard carbon ultrafine powder washing method according to claim 10, wherein, The steps of supplying washing liquid to the acid washing tank, the neutral washing tank and the alkaline washing tank comprise: the acid storage tank, the neutral storage tank and the alkaline storage tank respectively store washing liquid with corresponding pH, and the concentration of the washing liquid is monitored in real time by a concentration sensor; The pressure control unit of the acidic storage tank maintains the pressure in the tank higher than the parallel acidic washing tank, drives the acidic washing liquid to continuously flow into the acidic washing tank, and replenishes the washing liquid lost due to filtration; Similarly, the neutral storage tank maintains the pressure higher than the parallel neutral washing tank, and continuously replenishes the neutral washing liquid; Similarly, the alkaline storage tank maintains the pressure higher than the parallel alkaline washing tank, and continuously replenishes the alkaline washing liquid; The pressure control unit of the cross-flow tank maintains the pressure gradient of the acidic washing tank, the neutral washing tank and the alkaline washing tank, and drives the suspension to flow through the three washing tanks in turn.

Images